Self-propelled civil engineering machine and method of controlling a self-propelled civil engineering machine

ABSTRACT

The invention relates to a self-propelled civil engineering machine, and in particular to a slipform paver, road paver or road milling machine, and to a method of controlling a self-propelled civil engineering machine. The civil engineering machine according to the invention has a control unit which is configured to determine data which defines the position and/or orientation of a reference point on the civil engineering machine in relation to a reference system (X, Y, Z) independent of the position and orientation of the civil engineering machine. The reference system (X, Y, Z) independent of the machine-related reference system (x, y, z) may be selected as desired, and there is thus no need for the positions of various reference points to be plotted on the ground.

The invention relates to a self-propelled civil engineering machine, andin particular a road milling machine, road paver or slipform paver, andto a method of controlling a self-propelled civil engineering machineand in particular a road milling machine, road paver or slipform paver.

There are a variety of known kinds of self-propelled civil engineeringmachines. In particular, these machines include the known slipformpavers, road pavers and road milling machines. The characteristicfeature of these self-propelled civil engineering machines is that theyhave a working unit having working means for producing structures on theground or for making changes to the ground.

In the known slipform pavers, the working unit comprises an arrangementfor moulding flowable material and in particular concrete, whicharrangement will be referred to in what follows as a concrete mould.Structures of different types, such as crash barriers and road gutters,can be produced with the concrete mould. A slipform paver is describedEP 1 103 659 B1 (U.S. Pat. No. 6,481,924) for example.

The known road pavers generally have a screed as their working unit. Thescreed is so arranged, at that end of the road paver which is at therear looking in the direction of paving, that it is supported by a lowersliding plate on the material of the road covering being laid and apre-compression of the material thus takes place.

The working unit of the known road milling machines is a millingarrangement which has a milling drum fitted with milling tools, by whichmilling drum material can be milled off the ground over a preset workingwidth.

The known self-propelled civil engineering machines also have a driveunit which has drive means to allow movements in translation and/orrotation to be performed, and a control unit for controlling the driveunit in such a way that the civil engineering machine performs movementsin translation and/or rotation on the ground.

When self-propelled civil engineering machines are controlledautomatically, the problem arises that a preset reference point on thecivil engineering machine has to move precisely along a preset curve inspace on the ground, in order for example to enable a structure of apreset shape to be produced on the ground in the correct position and inthe correct orientation.

A known method of controlling slipform pavers presupposes the use of aguiding wire or line which lays down the desired curve along which thereference point on the civil engineering machine is to move. Elongatedobjects, such as crash barriers or road gutters for example, can beproduced effectively by using a guiding wire or line. However, the useof a guiding wire or line is found to be a disadvantage when structuresof small dimensions, such as cigar-shaped traffic islands for example,which are distinguished by extending for small distances and havingtight radiuses, are to be produced.

It is also known for self-propelled civil engineering machines to becontrolled by using a satellite-based global positioning system (GPS). Acivil engineering machine having a GPS receiver is known from U.S. Pat.No. 5,612,864 for example.

It is a disadvantage that the plotting of the position of an objectusing a master measurement system to control the civil engineeringmachine calls for a great deal of technical cost and complicationbecause the construction project will be complex and the object has tobe fitted into it. What is particularly costly and complicated is theplotting which has to be done of the positions of various referencepoints in the measurement system. This cost and complication can only bejustified for large objects. For small objects on the other hand thecost and complication is disproportionately high.

Another disadvantage of the objects being fitted into the complexbuilding project lies in the fact that in practice, with small objects,allowance often has to be made for fixed points, such for example asexisting hydrants or water outlets on the site, which may possibly notbe situated precisely at the points at which they were entered in theplans. Should the project data not agree with the actual local facts,the project data has to be amended off the site in the office atrelatively high cost and the amended project data then has to be read inagain on the site.

The object underlying the invention is therefore to provide aself-propelled civil engineering machine, and in particular a roadmilling machine, a road paver or a slipform paver, which can moveautomatically, without any great cost or complication in the plotting ofposition and with high accuracy, along a desired curve extending forrelatively short distances of travel and having tight radiuses. Anotherobject is to specify a method which allows a self-propelled civilengineering machine to be controlled automatically, without any greatcost or complication in the plotting of position and with high accuracy,along a desired curve extending for relatively short distances of traveland having tight radiuses.

The self-propelled civil engineering machine according to the inventionhas a control unit which has means for presetting a given geometricalshape for the structure to be produced or the ground to which changesare to be made. This given shape may for example be a traffic island inthe shape of a cigar. It may be entered or selected by the operator ofthe machine.

The control unit of the self-propelled civil engineering machineaccording to the invention also has means for determining data whichdefines the position and/or orientation of a reference point on thecivil engineering machine in relation to a reference system which isindependent of the position and orientation of the civil engineeringmachine. The reference system independent of the machine-relatedreference system can be selected as desired, and there is thus no needfor the positions of various reference points to be plotted on theground.

The operation of the control system according to the invention of thecivil engineering machine is based on the civil engineering machinebeing moved to a preset starting point on the ground which can be freelyselected. At the preset starting point the civil engineering machine isaligned in a preset orientation. The position and orientation of theobject are thus laid down. Consequently, the object can always beoptimally positioned on the ground with due allowance made for anypossible fixed points. The starting point may for example be sited atthe corner of a gutter already present on the ground whose position neednot exactly correspond to the layout plan.

As well as this, the control unit of the civil engineering machine alsohas means for determining data defining a desired curve, the desiredcurve being the curve along which the reference point (R) on the civilengineering machine is to move in the reference system (X, Y, Z)independent of the position and orientation of the civil engineeringmachine. The means for determining data defining the desired curve areso designed that the data defining the desired curve is determined onthe basis of the preset geometrical shape of the structure to beproduced or the ground to which changes are to be made and on the basisof the position and orientation of the reference point (R) on the civilengineering machine in the reference system (X, Y, Z) independent of theposition and orientation of the civil engineering machine.

The data which defines the desired curve may be the distance covered bythe desired curve and/or its curvature. This data is dependent on theshape of the object.

In a preferred embodiment, the means for controlling the drive unit areso designed that the drive unit is so controlled, as a function of theposition and orientation of the reference point in the reference systemindependent of the position and orientation of the civil engineeringmachine, that the distance between the desired position of the civilengineering machine, as defined by the desired curve, and its actualposition, and/or the difference in direction between the desireddirection, as defined by the desired curve, and the actual direction, isminimal. The control algorithms required for this purpose are well knownto the person skilled in the art.

An embodiment of the invention which is a particular preference makesprovision for use to be made of a satellite-based global positioningsystem (GPS) to determine the position and/or orientation of thereference point on the civil engineering machine. The reference systemindependent of the position and orientation of the civil engineeringmachine is thus the reference system of the satellite-based globalpositioning system, whose position and direction relative to themachine-related reference system constantly change as the civilengineering machine moves over the ground. The civil engineering machinehas a first and a second DGPS receiver (rover) for decoding the GPSsatellite signals from the satellite-based global positioning system andcorrecting signals from a reference station for determining the positionand/or orientation of the civil engineering machine, the first andsecond DGPS receivers being arranged in different positions on the civilengineering machine.

However, rather than by means of a satellite-based global positioningsystem, the position and/or orientation of the reference point may alsobe determined with a non-satellite measurement system. The only thingthat is crucial is for the control unit to receive data defining theposition and orientation of the reference point.

In a further preferred embodiment, the control unit has an input unithaving means (7B) for the input of parameters which define thegeometrical shape of the structure to be produced or the ground to whichchanges are to be made. These parameters may for example be parameterswhich define the length of a straight line and/or the radius of an arcof a circle. It is assumed in this case that the object can be brokendown into straight lines and arcs. This can be done for example in thecase of a traffic island in the shape of a cigar. However, it is alsopossible for other geometrical figures to be defined by the parameters.

In a further preferred embodiment, the control unit has an input unithaving means for selecting one geometrical shape from a plurality ofpreset geometrical shapes, the plurality of geometrical shapes beingstored in a storage unit which co-operates with the input unit. Theadvantage of this is that the data defining the geometrical shape doesnot have to be created afresh and instead recourse may be had to datasets which have already been created. A choice may for example be madebetween a circle and a cigar shape as an object.

A further embodiment which is a particular preference makes provisionfor means for modifying a preset geometrical shape. The advantage thatthis has is that the shape of a cigar for example may be selected andthe dimensions of the cigar can then be adjusted to suit the actualrequirements on the site.

Embodiments of the invention will be explained in detail in what followsby reference to the drawings.

In the drawings:

FIG. 1 is a side view of an embodiment of slipform paver,

FIG. 2 is a side view of an embodiment of road milling machine,

FIG. 3 shows a machine co-ordinate system related to a civil engineeringmachine together with the civil engineering machine, which is merelyindicated,

FIG. 4 shows a measurement co-ordinate system independent of theposition and orientation of the civil engineering machine together withthe machine co-ordinate system and civil engineering machine which areshown in FIG. 3,

FIG. 5 shows the graph curves for curvature and direction for an objectin the shape of a cigar,

FIG. 6 is a view of the geometrical shape defining a cigar-shaped objectfor controlling the civil engineering machine, before it is transposedinto the measurement co-ordinate system,

FIG. 7 is a view of the desired curve defining a cigar-shaped object forcontrolling the civil engineering machine, after it has been transposedinto the measurement co-ordinate system,

FIG. 8 shows the distance between the desired position of the civilengineering machine as defined by the desired curve and its actualposition,

FIG. 9 shows the difference in direction between the desired directionof the civil engineering machine as defined by the desired curve and itsactual direction.

FIG. 1 is a side view of, as an example of a self-propelled civilengineering machine, a slipform paver which is described in detail in EP1 103 659 B1 (U.S. Pat. No. 6,481,924). Because slipform pavers as suchare part of the prior art, all that will be described here are thosecomponents of the civil engineering machine which are material to theinvention.

The slipform paver 1 has a chassis 2 which is carried by running gear 3.The running gear 3 has two front and two rear track-laying running gearunits 4A, 4B which are fastened to front and rear lifting pillars 5A,5B. The direction of working (direction of travel) of the slipform paveris identified by an arrow A.

The track-laying running gear units 4A, 4B and the lifting pillars 5A,5B are parts of a drive unit of the slipform paver which has drive meansto allow the civil engineering machine to carry out movements intranslation and/or rotation on the ground. By raising and lowering thelifting pillars 5A, 5B, the chassis 2 of the machine can be movedrelative to the ground to adjust its height and inclination. The civilengineering machine can be moved backwards and forwards by thetrack-laying running gear units 4A, 4B. The civil engineering machinethus has three degrees of freedom in translation and three degrees offreedom in rotation.

The slipform paver 1 has an arrangement 6, which is only indicated, formoulding concrete which will be referred to in what follows as aconcrete mould. The concrete mould is part of a working unit which hasworking means for producing a structure 10 of a preset shape on theground.

FIG. 2 is a side view of, as a further example of a self-propelled civilengineering machine, a road milling machine. Once again, the roadmilling machine 1 too has a chassis 2 which is carried by running gear3. The running gear 3 has two front and two rear track-laying runninggear units 4A, 4B which are fastened to front and rear lifting pillars5A, 5B. The road milling machine has a working unit which has workingmeans to make changes to the ground. This working unit is a millingarrangement 6 which has a milling drum 6A fitted with milling tools.

FIG. 3 shows the self-propelled civil engineering machine in amachine-related Cartesian co-ordinate system (x, y, z). The civilengineering machine may be a slipform paver, a road milling machine orany other civil engineering machine which has an appropriate workingunit. The present embodiment is a slipform paver 1 which has a concretemould 6. The slipform paver 1 and the concrete mould 6 are merelyindicated. It has the chassis 2, having the track-laying running gearunits 4A, 4B, and the concrete mould 6.

The origin of the machine co-ordinate system is at a reference point Ron the slipform paver 1, what is laid down as the reference point Rbeing that edge of the concrete mould 6 which is on the inside and atthe rear in the direction of travel. This edge corresponds to the outerboundary of the structure 10 to be produced. In the machine co-ordinatesystem, the reference point R is determined as follows:R=xR,yR,zR=0,0,0

The machine co-ordinate system is clearly defined by six degrees offreedom, with the lengths of travel dx, dy, dz defining the movements intranslation and the angles ω, φ, κ defining the three movements inrotation.

To simplify things, it will be assumed that the civil engineeringmachine is standing on flat ground and is not inclined. The angles ω andκ in rotation are thus each equal to zero. The machine co-ordinatesystem and the civil engineering machine are aligned to one another insuch a way that the angle φ in rotation is equal to zero as well.

It will also be assumed that the bottom edge of the concrete mould 6 isresting on the ground. This lays it down that the height zR of thereference point R is not to change as the civil engineering machinemoves over the flat ground.

FIG. 4 shows the machine co-ordinate system together with a Cartesianreference system, independent of the machine co-ordinate system (x, y,z), which will be referred to in what follows as the measurementco-ordinate system (X, Y, Z). The measurement co-ordinate system (X, Y,Z) may be selected at random. It remains in the same position andorientation as the civil engineering machine moves.

To control the drive unit, the civil engineering machine has a controlunit 7 which is merely indicated. The control unit 7 controls the drivemeans of the drive unit in such a way that the civil engineering machineperforms the requisite movements in translation and/or rotation on theground to enable it to produce the structure 10 or make changes to theground. The control unit 7 comprises all the components which arerequired to perform calculating operations and to generate controlsignals for the drive means of the drive unit. It may form aself-contained unit or it may be part of the central control system ofthe civil engineering machine.

To allow the drive unit to be controlled, the position and/ororientation of the reference point R of the civil engineering machine inthe machine co-ordinate system (x, y, z) is transposed into themeasurement co-ordinate system (X, Y, Z) independent of the movements ofthe civil engineering machine.

In the present embodiment, the position and orientation of the referencepoint R are determined using a satellite-based global positioning system(GPS), which is only indicated in FIG. 4. However, rather than asatellite-based positioning system what may also be used is anon-satellite terrestrial measuring system (a total station). Becausethe requirements for the accuracy with which position and orientationare determined are stringent ones, what is preferably used is thatsatellite-based global positioning system which is known as thedifferential global positioning system (DGPS). The GPS-based method ofdetermining orientation is based in this case on the measurement ofposition by two DGPS receivers (rovers) which are arranged at differentpoints S1, S2 on the civil engineering machine.

The two DPGS receivers S1 and S2 are merely indicated in FIGS. 3 and 4.The case assumed is the more general one where the DGPS receiver S1 andthe DGPS receiver S2 are situated near the origin of the machineco-ordinate system in which the reference point R is sited, the positionand orientation of which reference point R are determined in themeasurement co-ordinate system.

The positions of the DGPS receivers S1 and S2 are determined in themachine co-ordinate system (x, y, z) by the co-ordinates S1=xs1, ys1,zs1 and S2=xs2, ys2, zs2. In the measurement co-ordinate system (X, Y,Z), the positions of the DGPS receivers S1 and S2 are determined byS1=XS1, YS1, ZS1 and S2=XS2, YS2, ZS2.

By using the two DGPS receivers S1 and S2, the control unit 7 employsthe GPS system to determine data which defines the position of the DGPSreceivers. From this data on position, the control unit 7 thencalculates the position and orientation of the reference point R on thecivil engineering machine near to which the two DGPS receivers aresituated. For this purpose, the control unit 7 performs a transformationwith the rotation matrix R to transform the co-ordinates at the pointsS1 and S2 which were measured in the measurement co-ordinate system (X,Y, Z) by the DGPS receivers S1 and S2 to give the reference point R

$\begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\{\Delta\; Z}\end{bmatrix} = {{\begin{bmatrix}{{{XS}\; 1} - {{xs}\; 1}} \\{{{YS}\; 1} - {{ys}\; 1}} \\{{{ZS}\; 1} - {{zs}\; 1}}\end{bmatrix}\begin{bmatrix}X \\Y \\Z\end{bmatrix}} = {{{\lbrack R\rbrack\begin{bmatrix}x \\y \\z\end{bmatrix}} + {\begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\{\Delta\; Z}\end{bmatrix}\begin{bmatrix}X \\Y \\Z\end{bmatrix}}} = {{\begin{bmatrix}{\cos\;\phi} & {{- \sin}\;\phi} & 0 \\{\sin\;\phi} & {\cos\;\phi} & 0 \\0 & 0 & 1\end{bmatrix}\begin{bmatrix}x \\y \\z\end{bmatrix}} + \begin{bmatrix}{\Delta\; X} \\{\Delta\; Y} \\{\Delta\; Z}\end{bmatrix}}}}$

The result is that the control unit determines the measurementco-ordinates of the reference point R on the concrete mould 6 of theslipform paver 1 in the measurement co-ordinate system (X, Y, Z):

$R = \begin{bmatrix}{Xr} \\{Yr} \\{Zr}\end{bmatrix}$

The control unit uses the following equation to calculate the angle Φgiving the direction of the civil engineering machine from theco-ordinates (XS2, XS1; YS2, YS1) of the measured points S1 and S2:Φ=arctan(XS2−XS1/YS2−YS1)

The control unit 7 controls the drive unit of the civil engineeringmachine in such a way that the civil engineering machine moves along apreset desired curve, i.e. the reference point R on the civilengineering machine moves along the desired curve.

In its general form, the desired curve can be defined as follows as afunction of distance traveled and curvature:

$\begin{bmatrix}X \\Y\end{bmatrix} = {{f(L)} = {{\int_{{si}\; n\;\alpha}^{{co}\; s\;\alpha}\left( {\mathbb{d}l} \right)} = \begin{bmatrix}{X\; 0} \\{Y\; 0}\end{bmatrix}}}$ where α = ∫K(𝕕l).

The curvature K is defined by K=1/R.

In the present embodiment, the slipform paver is to produce a trafficisland in the shape of a “cigar”. The geometrical shape of the cigar isdefined by a curve which comprises two parallel distances traveled andtwo arcs of a circle. What will be described in what follows will beonly that part of the curve which comprises the initial straight lineand the first semi-circular arc.

In the embodiment of the cigar, the curvature on the initial straightline is equal to zero. When the reference point R on the civilengineering machine moves along the first arc of a circle, the curvatureis constant. Once the civil engineering machine has ceased to move alongthe arc, the curvature once again becomes zero.

FIG. 5 shows the graph plot 9 for curvature and the graph plot 8 fordirection for the slipform paver when producing a cigar whosegeometrical shape is defined by a straight line of a length of 2 m andby a semi-circular arc whose radius is 2 m. The length and radiusconstitute in this case two parameters by which the geometrical shape ofthe cigar is preset. It will be clear that the graph plot for directionchanges as the civil engineering machine enters the arc.

The operator of the civil engineering machine first presets a givengeometrical shape such as the shape of a cigar for example. The operatoris free as to the geometrical shape he presets. FIG. 6 shows thegeometrical shape which is defined by a straight line “a” and asemi-circular arc “b”. Simply to make things clear, the geometricalshape of the cigar has been shown in a grid which relates to the machineco-ordinate system. The measurement co-ordinate system (X, Y, Z) hastherefore been indicated in FIG. 6 only to show the relationship betweenthe machine and measurement co-ordinate systems.

The control system according to the invention relies on a starting pointat which the production of the structure 10, such as a cigar forexample, begins first being freely selected for the slipform paver onthe ground. This starting point corresponds to the origin of the machineco-ordinate system, i.e. the reference point R (FIG. 6). The startingpoint may for example be situated next to a fixed point which is preseton the ground, such as a water inlet for example. The starting pointdefines the place at which the structure 10, such as the cigar forexample, is to be produced. The orientation of the civil engineeringmachine is preset freely at the starting point, thus laying down thedirection in which the structure 10, such as the cigar for example, isto extend.

The civil engineering machine is now driven to the selected startingpoint and is aligned in the preset orientation. This process is notautomated. The automated control of the civil engineering machine thentakes place.

The civil engineering machine having been positioned and aligned, thecontrol unit 7 determines for the starting point the data which definesthe position and orientation of the reference point R in the measurementco-ordinate system (X, Y, Z). This data which defines the position andorientation of the reference point R may be referred to as positiondata. For the subsequent control, the preset geometrical shape, such asthe cigar for example, then has to be transposed to the measurementco-ordinate system (X, Y, Z). On the basis of the preset geometricalshape of the structure to be produced or of the ground to which changesare to be made and on the basis of the position and orientation of thereference point R on the civil engineering machine in the measurementco-ordinate system (X, Y, Z) which is independent of the position andorientation of the civil engineering machine, the control unit 7determines data which defines a desired curve, the desired curve beingthat curve along which the reference point R on the civil engineeringmachine is to move in the measurement co-ordinate system (X, Y, Z). Thedata defining the desired curve may be referred to as curve data.

FIGS. 6 and 7 show the transfer of the freely preset geometrical shape(FIG. 6) to the measurement co-ordinate system (X,Y,Z) (FIG. 7), toallow the desired curve which defines the desired positions of thereference point in the measurement co-ordinate system (X, Y, Z) to belaid down.

The position and orientation of the reference point R on the civilengineering machine at the starting point having been determined and thedesired curve having been laid down, the control unit 7 puts the civilengineering machine into operation. The control unit now determines,continuously or at discrete increments of time, the actual position (Xr,Yr) and actual direction (Φ) of the reference point R on the civilengineering machine in the measurement co-ordinate system (X, Y, Z). Inso doing the control unit each time calculates the distance D betweenthe desired position P and the actual position (Xr, Yr) and thedifference in direction ΔΦ between the desired direction α and theactual direction Φ.

Using a preset control algorithm, a drive control component of thecontrol unit 7 calculates from the distance D and the difference indirection ΔΦ the value at the time of the manipulated variable for thedrive means of the drive unit in such a way that the distance D and thedifference in direction ΔΦ are minimal, i.e. in such a way that thereference point on the civil engineering machine moves along the desiredcurve. Control algorithms of this kind are well known to the personskilled in the art.

FIG. 8 shows the distance D between the desired position of a point onthe desired curve and the actual position (Xr, Yr) of the referencepoint R, while FIG. 9 shows the difference in direction ΔΦ between thedesired direction α and the actual direction Φ at a point on the desiredcurve. The correction to the steering is found as a function of thedistance D and the difference in direction ΔΦ (correction to steering=f(D, ΔΦ).

For the presetting of the geometrical shape, i.e. for the presetting ofa given object, the control unit has an input unit 7A which is onceagain merely indicated. The input unit 7A may also be referred to as ashape selection component 7A. In one embodiment, the input unit 7A hasmeans 7B in the form of, for example, a keyboard or a touch screen. Fromthe keyboard or touch screen 7B, the operator of the machine can entervarious parameters which define the geometrical shape. The operator mayfor example enter the length of the straight line and the radius of thearc for a cigar. The input unit 7A may also have means 7B, such forexample as a keyboard or touch screen once again, to enable onegeometrical shape which defines the desired object to be selected from aplurality of geometrical shapes which are stored in a memory unit 7C ofthe control unit. As well as for the input of parameters and/or theselection of geometrical shapes, a further embodiment of the controlunit 7 also makes provision for the modification of a geometrical shapewhich has been entered or selected. For example, a cigar whose straightlines are of a preset length and whose arcs are of a preset radius maybe selected and then, by entering new parameters for the length of thestraight lines and/or the radius of the arcs from the keyboard or touchscreen 7B, the cigar which was selected may be adjusted to suit theparticular requirements which exist at the site, the cigar being madesmaller or larger for example and in particular its width or lengthbeing changed.

As well as this, the input unit 7A also has means 7D, in the form of aswitch or push-button 7D for example, by which the civil engineeringmachine can be put into operation on the ground after the positioningand alignment. A switch or push-button 7D may also be provided on theinput unit 7A to enable the civil engineering machine to be stoppedbefore it has moved for the entire length of the desired curve. Thecivil engineering machine having been stopped, new parameters may, forexample, then be entered from the keyboard or touch screen 7B to changethe path followed by the curve and for example to change the height ofthe object being produced.

What is claimed is:
 1. A self-propelled civil engineering machine,comprising: a chassis; a working unit arranged on the chassis andoperable to produce a structure on the ground or to make changes to theground; a drive unit operable to perform movements of the civilengineering machine in translation and/or rotation on the ground; and acontrol unit configured to control movements of the civil engineeringmachine in translation and/or rotation on the ground, the control unitincluding: a shape selection component configured to preset ageometrical shape for the structure to be produced or for the ground towhich changes are to be made; a position data determination componentconfigured to determine position data to define the position and/ororientation of a reference point on the civil engineering machine inrelation to a reference system which is independent of the position andorientation of the civil engineering machine; a curve data determinationcomponent configured to determine curve data to define a desired curvebased on the preset geometrical shape of the structure to be produced orthe ground to which changes are to be made and based on a desiredposition and orientation of the preset geometrical shape in thereference system independent of the position and orientation of thecivil engineering machine, the desired curve being that curve alongwhich the reference point on the civil engineering machine is to move inthe reference system independent of the position and orientation of thecivil engineering machine; and a drive control component configured tocontrol the drive unit, as a function of the curve data defining thedesired curve, in such a way that the reference point on the civilengineering machine moves along the desired curve.
 2. The civilengineering machine according to claim 1, wherein: the desired positionand orientation of the preset geometrical shape in the reference systemindependent of the position and orientation of the civil engineeringmachine is based on the position of the reference point on the civilengineering machine in relation to the reference system which isindependent of the position and orientation of the civil engineeringmachine.
 3. The civil engineering machine according to claim 1, whereinthe curve data defining the desired curve defines the distance traveledalong the desired curve and/or its curvature.
 4. The civil engineeringmachine according to claim 1, wherein the drive control component isconfigured to control the drive unit, as a function of the positionand/or orientation of the reference point in the reference systemindependent of the position and orientation of the civil engineeringmachine, such that the distance between a desired position of thereference point, as defined by the desired curve, and an actual positionof the reference point, and/or a difference in direction between adesired direction of the civil engineering machine defined by thedesired curve and an actual direction of the civil engineering machine,is minimal.
 5. The civil engineering machine according to claim 1,wherein the position data determination component includes at least oneDGPS receiver for decoding GPS satellite signals from a satellite-basedglobal positioning system and correcting signals from a referencestation.
 6. The civil engineering machine according to claim 5, whereinthe position data determination component is configured to determine theorientation of the civil engineering machine as a function of the datafrom the at least one DGPS receiver, an alignment of a steerable drivetrack or wheel of the civil engineering machine and a distance driven bythe civil engineering machine.
 7. The civil engineering machineaccording to claim 1, wherein the position data determination componentincludes a first and a second DGPS receiver for decoding GPS satellitesignals from a satellite-based global positioning systems and correctingsignals from a reference station for determining the position andorientation of the civil engineering machine, the first and second DGPSreceivers being arranged in different positions on the civil engineeringmachine.
 8. The civil engineering machine according to claim 1, whereinthe position data determination component includes a first and a secondreceiver belonging to a non-satellite measuring system for determiningthe position and orientation of the civil engineering machine, the firstand second receivers being arranged in different positions on the civilengineering machine.
 9. The civil engineering machine according to claim1, wherein the shape selection component includes an input unit operablefor the input of parameters to define the geometrical shape of thestructure to be produced or the ground to which changes are to be made.10. The civil engineering machine according to claim 9, wherein theparameters are parameters which define the length of a straight lineand/or the radius of an arc of a circle.
 11. The civil engineeringmachine according to claim 1, wherein the shape selection componentincludes an input unit operable to select one geometrical shape from aplurality of pre-defined geometrical shapes.
 12. The civil engineeringmachine according to claim 11, wherein the control unit has a storageunit which co-operates with the input unit and in which the plurality ofpre-defined geometrical shapes are stored.
 13. The civil engineeringmachine according to claim 11, wherein the input unit is operable tomodify a pre-defined geometrical shape.
 14. The civil engineeringmachine according to claim 1, wherein the control unit is operable tostart the movement of the civil engineering machine at a preset startingpoint on the ground at which the civil engineering machine is in apreset position and orientation.
 15. The civil engineering machineaccording to claim 1, wherein the control unit is operable to stop themovement of the civil engineering machine along the desired curve. 16.The civil engineering machine according to claim 1, wherein the civilengineering machine is a road milling machine, the working unit having amilling arrangement having a milling drum.
 17. The civil engineeringmachine according to claim 1, wherein the civil engineering machine is aslipform paver, the working unit having an arrangement for mouldingflowable material.
 18. The civil engineering machine according to claim1, wherein the civil engineering machine is a road paver, the workingunit having a screed for shaping material.
 19. The civil engineeringmachine according to claim 1, wherein: the drive control component isconfigured to control the drive unit to steer the reference point on thecivil engineering machine to a point on the desired curve when thereference point is not located on the desired curve.
 20. A method ofcontrolling a self-propelled civil engineering machine, the methodcomprising: (a) presetting of a geometrical shape for a structure to beproduced or the ground to which changes are to be made; (b) determininga position of at least one identifiable point of the preset geometricalshape in a reference system independent of the position and orientationof the civil engineering machine; (c) determining of data which definesa position of a reference point on the civil engineering machine inrelation to the reference system independent of the position andorientation of the civil engineering machine; (d) determining of curvedata defining a desired curve, on the basis of the preset geometricalshape for the structure to be produced or the ground to which changesare to be made and on the basis of the position of the at least oneidentifiable point of the preset geometrical shape in the referencesystem independent of the position and orientation of the civilengineering machine, the desired curve being that curve along which thereference point on the civil engineering machine is to move in thereference system independent of the position and orientation of thecivil engineering machine; and (e) controlling of the civil engineeringmachine with a machine control unit, as a function of the data definingthe desired curve, in such a way that that the reference point on thecivil engineering machine moves along the desired curve.
 21. The methodaccording to claim 20, wherein: the position of at least oneidentifiable point of the preset geometrical shape in a reference systemindependent of the position and orientation of the civil engineeringmachine of step (b) is a starting position and orientation of thereference point on the civil engineering machine in relation to thereference system independent of the position and orientation of thecivil engineering machine of step (c).
 22. The method according to claim20, wherein: step (d) is performed with the machine control unit of thecivil engineering machine.
 23. The method according to claim 20, whereinstep (a) comprises inputting parameters defining the geometrical shape.24. The method according to claim 20, wherein step (a) comprisesselecting one geometrical shape from a plurality of geometrical shapes.25. The method according to claim 20, wherein: step (a) is performedwith the machine control unit of the civil engineering machine.
 26. Themethod according to claim 20, wherein the curve data defining thedesired curve defines the distance traveled along the desired curveand/or its curvature.
 27. The method according to claim 20, wherein thecivil engineering machine is so controlled, as a function of theposition of the reference point in the reference system independent ofthe position and orientation of the civil engineering machine, that adistance between a desired position of the reference point, as definedby the desired curve, and an actual position of the reference point,and/or a difference in direction defined by the desired curve between adesired direction of the civil engineering machine and an actualdirection of the civil engineering machine is reduced.